The San Francisco Composers Chamber Orchestra is a diverse group of Bay Area composer-performers whose artistic goal is to present, and to represent, the emerging new music of San Francisco, primarily through performances of their own compositions. This evening, the only musical assemblage known to have written and performed a concert in honor and commemoration of “our former ninth planet,” Pluto (presented at O1C in October), presents a program of stirring new works by SFCCO members and associates.